// VisualBoyAdvance - Nintendo Gameboy/GameboyAdvance (TM) emulator.
// Copyright (C) 1999-2003 Forgotten
// Copyright (C) 2004 Forgotten and the VBA development team

// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or(at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software Foundation,
// Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

#include <stdio.h>
#include <string.h>

#include "gbGlobals.h"

typedef struct
{
	u8    mask;
	u8    value;
	char *mnen;
} GBOPCODE;

static char *registers[] =
{ "B", "C", "D", "E", "H", "L", "(HL)", "A" };

static char *registers16[] =
{ "BC", "DE", "HL", "SP", // for some operations
  "BC", "DE", "HL", "AF" };   // for push/pop

static char *cond[] =
{ "NZ", "Z", "NC", "C" };

static char hexDigits[16] = {
	'0', '1', '2', '3', '4', '5', '6', '7',
	'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};

static GBOPCODE opcodes[] = {
	{ 0xff, 0x00, "NOP"            },
	{ 0xcf, 0x01, "LD %R4,%W"      },
	{ 0xff, 0x02, "LD (BC),A"      },
	{ 0xcf, 0x03, "INC %R4"        },
	{ 0xc7, 0x04, "INC %r3"        },
	{ 0xc7, 0x05, "DEC %r3"        },
	{ 0xc7, 0x06, "LD %r3,%B"      },
	{ 0xff, 0x07, "RLCA"           },
	{ 0xff, 0x08, "LD (%W),SP"     },
	{ 0xcf, 0x09, "ADD HL,%R4"     },
	{ 0xff, 0x0a, "LD A,(BC)"      },
	{ 0xcf, 0x0b, "DEC %R4"        },
	{ 0xff, 0x0f, "RRCA"           },
	{ 0xff, 0x10, "STOP"           },
	{ 0xff, 0x12, "LD (DE),A"      },
	{ 0xff, 0x17, "RLA"            },
	{ 0xff, 0x18, "JR %d"          },
	{ 0xff, 0x1a, "LD A,(DE)"      },
	{ 0xff, 0x1f, "RRA"            },
	{ 0xe7, 0x20, "JR %c3,%d"      },
	{ 0xff, 0x22, "LDI (HL),A"     },
	{ 0xff, 0x27, "DAA"            },
	{ 0xff, 0x2a, "LDI A,(HL)"     },
	{ 0xff, 0x2f, "CPL"            },
	{ 0xff, 0x32, "LDD (HL),A"     },
	{ 0xff, 0x37, "SCF"            },
	{ 0xff, 0x3a, "LDD A,(HL)"     },
	{ 0xff, 0x3f, "CCF"            },
	{ 0xff, 0x76, "HALT"           },
	{ 0xc0, 0x40, "LD %r3,%r0"     },
	{ 0xf8, 0x80, "ADD A,%r0"      },
	{ 0xf8, 0x88, "ADC A,%r0"      },
	{ 0xf8, 0x90, "SUB %r0"        },
	{ 0xf8, 0x98, "SBC A,%r0"      },
	{ 0xf8, 0xa0, "AND %r0"        },
	{ 0xf8, 0xa8, "XOR %r0"        },
	{ 0xf8, 0xb0, "OR %r0"         },
	{ 0xf8, 0xb8, "CP %r0"         },
	{ 0xe7, 0xc0, "RET %c3"        },
	{ 0xcf, 0xc1, "POP %t4"        },
	{ 0xe7, 0xc2, "JP %c3,%W"      },
	{ 0xff, 0xc3, "JP %W"          },
	{ 0xe7, 0xc4, "CALL %c3,%W"    },
	{ 0xcf, 0xc5, "PUSH %t4"       },
	{ 0xff, 0xc6, "ADD A,%B"       },
	{ 0xc7, 0xc7, "RST %P"         },
	{ 0xff, 0xc9, "RET"            },
	{ 0xff, 0xcd, "CALL %W"        },
	{ 0xff, 0xce, "ADC %B"         },
	{ 0xff, 0xd6, "SUB %B"         },
	{ 0xff, 0xd9, "RETI"           },
	{ 0xff, 0xde, "SBC %B"         },
	{ 0xff, 0xe0, "LD (FF%B),A"    },
	{ 0xff, 0xe2, "LD (FF00h+C),A" },
	{ 0xff, 0xe6, "AND %B"         },
	{ 0xff, 0xe8, "ADD SP,%D"      },
	{ 0xff, 0xe9, "LD PC,HL"       },
	{ 0xff, 0xea, "LD (%W),A"      },
	{ 0xff, 0xee, "XOR %B"         },
	{ 0xff, 0xf0, "LD A,(FF%B)"    },
	{ 0xff, 0xf2, "LD A,(FF00h+C)" },
	{ 0xff, 0xf3, "DI"             },
	{ 0xff, 0xf6, "OR %B"          },
	{ 0xff, 0xf8, "LD HL,SP%D"     },
	{ 0xff, 0xf9, "LD SP,HL"       },
	{ 0xff, 0xfa, "LD A,(%W)"      },
	{ 0xff, 0xfb, "EI"             },
	{ 0xff, 0xfe, "CP %B"          },
	{ 0x00, 0x00, "DB %B"          }
};

static GBOPCODE cbOpcodes[] = {
	{ 0xf8, 0x00, "RLC %r0"    },
	{ 0xf8, 0x08, "RRC %r0"    },
	{ 0xf8, 0x10, "RL %r0"     },
	{ 0xf8, 0x18, "RR %r0"     },
	{ 0xf8, 0x20, "SLA %r0"    },
	{ 0xf8, 0x28, "SRA %r0"    },
	{ 0xf8, 0x30, "SWAP %r0"   },
	{ 0xf8, 0x38, "SRL %r0"    },
	{ 0xc0, 0x40, "BIT %b,%r0" },
	{ 0xc0, 0x80, "RES %b,%r0" },
	{ 0xc0, 0xc0, "SET %b,%r0" },
	{ 0x00, 0x00, "DB CBh,%B"  }
};

static char *addHex(char *p, u8 value)
{
	*p++ = hexDigits[value >> 4];
	*p++ = hexDigits[value & 15];
	return p;
}

static char *addHex16(char *p, u16 value)
{
	p = addHex(p, value>>8);
	return addHex(p, value & 255);
}

static char *addStr(char *p, char *s)
{
	while (*s)
	{
		*p++ = *s++;
	}
	return p;
}

int gbDis(char *buffer, u16 address)
{
	char *p     = buffer;
	int   instr = 1;
	u16   addr  = address;
	sprintf(p, "%04x        ", address);
	p += 12;

	u8 opcode = gbReadMemoryQuick(address);
	address++;
	char *    mnen;
	GBOPCODE *op;
	if (opcode == 0xcb)
	{
		opcode = gbReadMemoryQuick(address);
		address++;
		instr++;
		op = cbOpcodes;
	}
	else
	{
		op = opcodes;
	}
	while (op->value != (opcode & op->mask))
		op++;
	mnen = op->mnen;

	u8  b0, b1;
	s8  disp;
	int shift;

	while (*mnen)
	{
		if (*mnen == '%')
		{
			mnen++;
			switch (*mnen++)
			{
			case 'W':
				b0 = gbReadMemoryQuick(address);
				address++;
				b1 = gbReadMemoryQuick(address);
				address++;
				p      = addHex16(p, b0|b1<<8);
				instr += 2;
				*p++   = 'h';
				break;
			case 'B':
				p    = addHex(p, gbReadMemoryQuick(address));
				*p++ = 'h';
				address++;
				instr++;
				break;
			case 'D':
				disp = gbReadMemoryQuick(address);
				if (disp >= 0)
					*p++ = '+';
				p += sprintf(p, "%d", disp);
				instr++;
				break;
			case 'd':
				disp = gbReadMemoryQuick(address);
				address++;
				p    = addHex16(p, address+disp);
				*p++ = 'h';
				instr++;
				break;
			case 'b':
				// kind of a hack, but it works :-)
				*p++ = hexDigits[(opcode >> 3) & 7];
				break;
			case 'r':
				shift = *mnen++ - '0';
				p     = addStr(p, registers[(opcode >> shift) & 7]);
				break;
			case 'R':
				shift = *mnen++ - '0';
				p     = addStr(p, registers16[(opcode >> shift) & 3]);
				break;
			case 't':
				shift = *mnen++ - '0';
				p     = addStr(p, registers16[4+((opcode >> shift) & 3)]);
				break;
			case 'P':
				p = addHex(p, ((opcode >> 3) & 7) * 8);
				break;
			case 'c':
				shift = *mnen++ - '0';
				p     = addStr(p, cond[(opcode >> shift) & 3]);
				break;
			}
		}
		else
			*p++ = *mnen++;
	}
	for (int i = 0; i < instr; i++)
	{
		u16 a = addr + i;
		addHex(buffer+5+i*2, gbReadMemoryQuick(a));
	}
	*p = 0;
	return instr;
}
